C ... -- 4 -
CONTE PORARY ETRICAL 
OCUMENT l 1ION OF 
ST UCTURES -ICH E 
PART OF THE CULTURAL 
ERITAGE 
Mojca Kosmatin Fras, Katja Oven, Miran Janežič 
Institute of Geodesy and Photogrammetry FGG, Ljubljana 
Received f or publication: September 22 1998 
Preparecl f or publication: September 22 1998 
Abstract 
The paper presents the recent development of the 
Photogrammetry Department of the Institute of Geodesy and 
Photogrammehy FGG in the field of metrical documentation 
of structures which are part of the cultural heritage. Work 
was focused on developing up-to-dale metrical 
documentation of structures, promoting team work, 
promoting the use of"photogrammetry in the humanities and 
preparing recommendations for technical standards for 
structures. A review of the work is supplemented with 
examples of implemented projects. 
Keywords: architectural photogrammetry, close range 
photogrammetly, computer graphics, three-dimensional 
mode/s 
1 INTRODUCl'l!ON 
In the recent few years, the Photogrammetry Department of the Institute of 
Geodesy and Photogrammetry FGG has been intensely engaged in introducing 
contemporary forms of photogrammetric documentation for the needs of protecting 
the cultural heritage. During this period, the Institute has acted as contractor for the 
Cultural Heritage Office of the Republic of Slovenia and completed a larger number 
of projects which are part of an umbrella project entitled Surveys. In 1991, the then 
Institute of the Republic of Slovenia for the Protection of the Natural and Cultural 
Heritage placed a five-year project entitled Surveys - Technical Photographs of More 
Demanding Structures which are part of the Cultural Heritage into the programme 
of the Ministry of Culture. This was the first time that the Slovenc monument 
protection service discussed the documenting of our cultural heritage more 
comprebensively as an important part of its activities (Grobovšek, 1996). Since the 
project was successful and bccame well-established, it is still being carried out. 
Geodetski vestnik 42 ( 1998) 4 
he basic goal of thc projects was to prepare photogrammetric documentation for 
monuments, but we also sought new and more appropriate product forms, more 
advanced technological solutions and improvements to the entire process. Together 
with the clients and conservators from regional Institutes for the Protection of the 
Natural and Cultural Heritage, we are building an increasingly more comprehensive 
system of documentation which will be briefly presented below. We received 
recognition for our achievements in this field (a Doležal Award) at the last World 
ISPRS Congress in 1996 in Vienna, while our presentations and publications abroad 
have received favourable responses and generated interest in our program solutions 
and implementation concept. 
2 DESCRIPTION OF OUR DEVELOPMENT 
Our development in the above-mentioned projects is oriented into: 
o teamwork on projects 
• promotion of photogrammetry in the humanities 
• production of technologically advanced forms of documentation 
• preparation of recommendations for standards. 
2.1 Teamwm:k on projects 
Professionals from various technical and humanities fields meet in this work, therefore at least a general knowledge of several fields is required from 
participants. The extent, content and form of the products are agreed with the 
conservators. Various options are presented and we attempt to find the best possible 
solution together. The structures differ in their external appearance, condition, type 
of work required, etc., therefore the procedures and products used are never 
completely the same. Sometimes it is also necessary to harmonize various work 
methods on a single project. The success of such cooperation has been demonstrated 
in the implementation of the Tito Square project in Koper ( commissioned by the 
Rižana water supply company) and professionally coordinated by the Intermunicipal 
Institute for the Protection of the Natural and Cultural Heritage, Piran), in which 
photogrammetric, georadar and thermographic measurements were geolocated in a 
unified form. We were able to compare the products directly and interesting results 
were obtained. To give only one example: the photogrammetrically evaluated damage 
to the pavement matched the georadar interpretation of findings below the surface. 
The project was presented at an international conference of the ICAP (International 
Committee on Architectural Photogrammetry) in Goteborg (Guček et al., 1997), and 
the organizers held it up as a model of interdisciplinary cooperation for other 
participants. 
2.2 Promotion of photogrammetry in the humanities 
Together with the Cultural Heritage Office of the Republic of Slovenia we have 
thus far prepared two exhibitions at the Ljubljana Cultural Information Centre, 
the first one in 1996 (Documenting of the Cultural Heritage) and the second one in 
1998 (Socerb Castle -The Future of Cultural Monuments). Upon the opening of the 
first exhibition, a round table discussion was organized about problems in 
documenting structures which are part of the cultural heritage. Herc, for the first 
Geodetski vestnik 42 (1998) 4 
tirne, representatives of different professions discussed this matter publicly. A 
thematic issue of a journal issued by the Cultural Heritage Office of the Republic of 
Slovenia of the Ministry of Culture was titled "Photogrammetry as a Method of 
Documenting Cultural Heritage". A film (VHS, 15 minutes) entitled The Socerb 
Castle - Preservation of a Cultural Monurnent was shown at the opening of the 
second exhibition, at which we presented an example of the work of conservators and 
photogrammetrists. 
2.3 Prnduction of technologically adv::mced forms of documentation 
This topic is fairly extensive, therefore only the main developmental phases and 
achievements will be described. About three years ago we focused our work into 
3D production of documentation of structures which are part of the cultural heritage. 
Today we find that our decision was correct, because trends around the world are 
identical (Atkinson, Gruen, 1996). Development was based on high-power personal 
computers and the available software (AutoCAD among others), to which we added 
our own programs. The first such program was in 3D (Janežič, 1996), and it was later 
upgraded and renamed ARCHOS. This program enables us to make spatial models 
of structures from photogrammetric and geodetic data about it The basic principle 
employed in making models is to preserve to the greatest possible extent the level of 
accuracy of the capture of the original spatial data. Our development thus went from 
the first attempts at modelling individual facades and the production of wire rnodels 
of structures and surface models to photorealistic models. W e placed the highest 
priority on metrical quality, but visualisation contributed to greater attractiveness and 
a clearer presentation. A fcw interesting projects are presented in Chapter 3. 
2.4 Preparation of recommendations for standards 
Without consistently documented procedures and organization of photogrammetric data and results, there is a risk of loss of information or data 
abuse (Bitelli, 1997). We agree with this assertion, because we have also found that, 
occasionally, incomplete documentation is submitted and archived. Clients usually 
receive only graphical products and photogrammetric images. The results cannot be 
checked or upgraded unless an entire report is available, containing all data, from 
field measurements and identification of reference points to orientation protocol, etc. 
The preparation of minimum standards for technical documentation has therefore 
become an important part of the Surveys project. This issue is quite extensive 
and complex and requires a thorough knowledge of the field. On the basis of our 
experience, study of foreign literature and professional contacts abroad, we have so 
far prepared recommendations for standards for the technical part of the metrical 
documentation of structures. In the report we dcfined the entire photogrammetric 
process, from field measurernents to possible products, and designed detailed 
technical requirements for each phase. We also determined the compulsory elements 
that reports must contain. Particular attention was paid to protective 
photogrammetric surveys, with the objective of achieving such execution of 
photogrammetric and geodetic surveying of structures of cultural heritage with 
methods that would enable us, if necessary, to metrically reconstruct the object as a 
spatial whole with its basic elements, i.e. its facades. Due to limitations in funding, it 
Geodetski vestnik 42 ( 1998) 4 
is possible to produce cornplete metrical docurnentation, from irnages to the final 
product, for only a few structures. This method, however, would enable us to 
document a greater number of structures, and the evaluation of irnages could be 
performed later, if necessary. Campaigns for protective photography are in progress. 
3 EXAMPLES 
3.1 Socerb Castle 
In this project, we developed a systern of comprehensive structure docurnentation on the basis of a 3D model. The practical objective of the project was to produce 
metrical documentation of the existing condition of the castle at differcnt levels of 
accuracy and in different forms. A geodetic site plan existed for the castle and its 
surroundings, as well as an approximate 3D surface model of the castle's exterior. 
The conditions for fiel~ work were difficult, because the castle is partially inaccessible 
(it is built on a cliff), its walls are made of rock and the surfaces of its exterior facade 
are irregular. The castle was originally much higher, but it was destroyed by a fire 
caused by lightning. 
Figure 1: Computer visualization of the Socerb Castle 
Additional geodetic and photogrammetric measurements first improved the accuracy 
of the existing surface model. The consistency of the model's topology was checked 
and corrected. Due to the stone structure of the facades, we used model rendering 
(adjustment of texture to the surfaces) with photogramrnetric irnages (possibility of 
combining vectors and rasters provided by AutoCAD r14). A so-called photo model 
was obtained. This term also appears in foreign professional literature 
Geodetski vestnik 42 ( 1998) 4 
(3D-Photomodelle Kraus, 1997). The mean error of the produced model is 
± 20 cm. Certain facades and details needed to be evaluated at a greater accuracy, 
i.c. ± 2 cm, therefore digital ortophotographs were made. Digital ortophoto plans 
are a very suitable form of mctrical documentation, because the interpretation of 
details is performed by the professionals themselves. The use of functions and filters 
for the digital processing of images is an additional help. Photomosaics were 
prepared for certain parts of the castle and some details were photographed for 
purposes of interpretation. In order to be able to unite all these different products 
into a single system, we produced a photographic-attribute database, which was 
connected with the produced three-dimensional model through graphic icons. By 
clicking the icons, the following information can be obtained on the existing 
documentation: is it photography, photomosaic or digital orthophoto; are thc images 
analogue or digital; what is the accuracy of the product, etc. If the image is in digital 
form, we can view it, if it is in analogue form, we can find out where it is located in 
the archives. Notes can bc added to data. The described contents of the database 
were prepared especially for this project, but any information can be included. For 
this purpose we produced our own program cntitlcd FOTO-AT. Finally, we also 
created a visualization of the model in the 3D Studio MAX r2 program, whereby we 
used standard rendering parameters. In our further work on the project, we are 
planning to produce reconstruction of the castle on the basis of the existing pictorial 
materials (Valvasor's drawings, a photograph of the castle before work on the 
structure in 1925). 
3.2 Ruins of the Vodriž casUe near Slovenj Gradec 
In the opinion of Dr. Ivan Stopar, a reputed Slovenc medievalist and castleologist, the ruins of the Vodriž castle are extremely important, because they are the only 
ones in Slovenia that have preserved certain medieval construction elements. 
Extensive conservation work is being prepared for the structure, therefore the 
production of metrical documentation was essential. From the technical point of 
view, documenting of ruins is difficult, because their surroundings are usually covered 
in vegetation, their locations are difficult to access and there is a large danger of 
crumbling. Thc use of remote measurement is therefore the most suitable. Thc 
remains of the Vodriž castle have all of thc above-mentioned technical properties of 
ruins. The object lies on a hill and is surrounded by a tall forest. The technical 
conditions for photography were very difficult, because the lines of sight are steep 
and photogrammetric images are highly oblique. In addition to the ruins themselves, 
the nearby terrain had to be measured as well. 
A special method of facade edge measurement was created for this project. Due 
to poor conditions for photogrammetry it was not possible to produce 
stereoscopic images, but on!y individual convergent images, which are suitable for 
point photogrammetric evaluation. The greatest difficulty was the large interpretation 
uncertainty of structure edges. All photogrammetric images were taken with a 
Rolleimetric 6006 me1:ric camera. Analogue photographs were scanned and included 
in the photographic-attribute database, especially all the important details of 
medieval construction elements. In further work, it will be possible to perform 
simulations of castle reconstructions, check hypotheses, prepare conservators' 
Geodetski vestnik 42 (1998) 4 
proposals and variants of soluiions, etc., \Vith such a ~11odel, but above all it 'Nil! be 
possible to monitor all conservation work on the object. 
Figure 2: Swface model of the Vodriž Casile ruins 
3.3 Cisterdan monastery in Stična 
Figure 3: Three-dimens;onal model of the Stična monaste1y 
Geodetski vestnik 42 (1998) 4 
This project v1ill remain embeddecl in our memory for a long tirne, because it has been our largest project v1ith respect to the extent of documentation prepared. 
At first glance, the complex is sirnple to measurc, but its size is quite considerable. 
From geodctic and extensive photogrammetric measurements V✓C have produced an 
accurate three-dimensional model of the monastery's exterior. The model is basically 
roade of wire mesh, but in order to achieve a better visual effect, certain parts of the 
facades were made in a surface !Y1anner. The cletails of external facades (windows, 
the door, portal, ete,) ,vere rnade in 3D with ali the details. The produced model will 
serve for entry of the existing manual measurements and supplementing of 
documentation (elements of facades in the inner courtyard, the church attic with a 
preserved upper floor of a Rornanesque basilica, cloister, etc.). 
3.4 Novo Mesto Chapter Ctmn:h 
For the production of computer animation of the proposal for new location of the tabernacle, we first produced a surface model of the presbytery's interior from 
the existing photogrammetrically made plans (ground floor, cross sections). The 
model was equipped with tcxtures in the 3D Studio MAX r2 program. The position 
of the tabernacle was changed and the visual effect of this change on various views in 
the room were studied. We also produced a virtual stroll through the room ( on 
computer and VHS) for the existing and the proposed new tabernacle locations. 
Figure 4: Proposa l far new localion of the tabernacle in the presbyte,y 
Geodetski vestnik 42 (1998) 4 
4 CONCLUSION 
e have succeeded in establishing a modem ancl operational concept of 
documenting structures of cultural heritage in Slovenia. The solutions 
constantly needed to be adapted to the specific requirements of indiviclual prnjects, 
but this made work in this field very interesting and creative. However, for the tirne 
being, the various possibilities for the use of such documentation by profcssionals in 
monurnent protection institutions are insufficiently exploited, the reason being 
insufficient computer equipment and computing knowledge at the regional institutes 
for the protection of the natura! and cultural heritage. This problem is being dealt 
with in agreement with the Cultural Heritage Office of the Republic of Slovcnia. 
Acknowledgement 
We gratefully aclmowledge the assistance of Mr. Jovo Grobovšek, state vice-secretary 
at the Cultural Heritage Office of the Republic of Slovenia and Surveys project 
coordinator, who through his understanding supports high-quality development in the 
field of documenting cultural heritage. We vvould also like to thank other associates 
at the Photogrammetry Department of the IGF, Stane Tršan, Boža Parcer and Jure 
Fegic, who with their dedicated work have contributed to successful execution of the 
projects. 
Refe:rences: 
Atkinson, KB., Close Range Photogrammetly and Machine Vision. VVhittles Publishing, 1996. 
Pogl. 4, Development of digital methodolology and systems (avtor Gruen, A.)in Pag/. 10, 
Architectural and archaeological photogrammet1y ( author Dallas, R. WA.) 
Bitelli, G., On the management and integration of photogrammetric data and metadata. Perugia, 
ISPRS WG Vl/3, 1998 
Grobovšek, J., Nacionalni projekt Izmere, pot do sistemskega reševanja kulturne dediščine. Vestnik, 
Uprava Republike Slovemj'e za kulturno dediščino, Ljubljana, 1996, no. 15, p. 5-11 
Guček, M. et al., Koper Platea Communis: beneath the medieval square - New approaches in 
Slovenian conservation policy. !CAP lntemational Symposium, Goeteborg, 1997 
Janežič, M., Izdelava tridimenzionalnih modelov objektov kulturne dediščine iz fotogrametrično 
zajetih podatkov. Vestnik, Uprava Republike Slovenije za kulturno dediščino, Ljubljana, 1996, 
no. 15, p. 57-69 
Kosmatin, Fras, M., Tridimenzionalna metrična dokumentacija in digitalni ortofoto Marijine 
rotunde v Kopru. Annales, Koper, 1997, no. 10, p. 91-96 
Kosmatin, Fras, M. et al., Rotunda Carmine - Case Study. Proceedings of the lntemational 
Conference: Studies in Ancient Structures, Istanbul, 1997, p. 115-124 
Kraus, K, Herausfordenmgen an die Photogrammetrie und Femerkundung Zukuenftige Aspekte 
in der Forschung. Photogrammetrie-Femerkundung-Geoinformation, Stuttgart, 1997, no. 6, p. 
341-346 
Review: mag. Vasja Bric 
Franci Vrhovec 
Geodetski vestnik 42 (1998) 4